Yes, you can set it to allow from any email ... which I actually don't use.
What I've done is use the plugin "Contact Form 7" which will email the contents of the "contact" form to a local account which I then use as the account for posting by email. IE: I don't accept posting from outside/random email addresses only this one specified in the post. This means all posts show as posted by "admin" as there are no other registered users.
The form has a required field for the person to put their "name" so I was wondering if that name could show as the poster instead of "admin".
I've been experimenting with another plugin called "User Submited Posts" which allows posting without an account and will swap out user admin in the string "Posted by Admin on November ...." with the name entered in the name field. If you click the name you will be taken to admin's profile but at least it shows at first glance the proper author.
I hope that makes sense. I much prefer using "Contact Form 7" and your plugin as a way for unregistered people to submit content but this one thing is sort of a game changer for my client.